In today's automobiles, it is becoming more common to provide both an analog and digital speed display. In a typical arrangement, an analog gauge cluster may be provided having both a speedometer and a tachometer and one or more system gauges such as a fuel gauge, a temperature gauge, an oil gauge, etc. A digital display, often located adjacent the analog gauge cluster or as a part of the analog gauge cluster, may typically include an LCD screen capable of displaying information such as a digital readout of the vehicle speed, and/or digital readouts of information associated with one or more of the other analog gauges, for example. Such combined displays are sometimes referred to as combimeters.
In some arrangements, the digital speed display may be associated with a cruise control system. For example, a driver may set the cruise control speed based on the speed indicated on the digital speed display. Using the digital speed display, the user can set a more precise speed to be maintained by the cruise control system.
One problem that may arise when displaying both an analog and a digital speed to a driver is that the analog gauge display may indicate a different speed than the digital display. The differences between the two displays can lead to driver distraction and/or irritation. Moreover, although both the analog gauge and digital gauge may be working properly, some drivers may register complaints due to the discrepancy. These complaints can be costly in that auto dealers and/or manufacturers must spend time and resources to address the concerns. Ultimately, however, since the discrepancy is inherent in the system, nothing can be done to rectify the situation beyond educating the consumer that some discrepancy may exist. While some consumers may accept such outcome, other drivers may remain dissatisfied.
In a typical prior art system, the analog speedometer unit sends a speed value to a control unit which in turn outputs a digital speed value to a digital display. Because of needle position variations from one analog speedometer to the next, the speed indicated by the needle of a given analog speedometer will often vary from the digital speed value displayed by the digital display, even though both the analog speedometer and the digital display are receiving signals corresponding to a common speed. In other words, a given analog speedometer display input value can result in different indicated speeds on various analog speedometers, but should always generally result in the same speed value being displayed on a digital display.
Prior art systems have attempted to minimize the difference between the analog speedometer and the digital display by utilizing the center point of the speedometer tolerance range. Such systems generally apply a correction factor to the digital display readout based upon an average deviation between the actual speed and the displayed speed for a given analog speedometer. As will be appreciated, such systems do not eliminate the problem since most gauges will not have an offset that corresponds to the average deviation. Thus, in many instances the discrepancy between the two gauges will remain, although on a reduced basis, and still result in driver distraction and/or irritation, and/or consumer complaints.